1. Field of the Invention
The present invention relates to a technique for setting cell coverage in a radio communication system and, more particularly, to a technique for setting an optimal cell coverage, reflecting the characteristics of a base station intended to be actually established and a user's demands for the talking quality.
2. Description of the Related Art
A cell coverage determines the number of base stations to be established (this is relative to the establishment cost), and the talking quality. If a cell coverage is smaller, the number of base stations increases. If the cell coverage is larger, the number of base stations decreases but the talking quality is deteriorated. Therefore, it is very important to optimally set a cell coverage in designing a cell for a cellular or multi-cellular radio private exchange.
To decide the cell coverage, it is a general procedure to establish a signal generator at a place where a base station is intended to be established so that the signal generator generates a signal of a band which is used by the base station equipment. Then, the strength of the signal is measured by moving a signal analyzer. The measured signal is then regarded as a Received Signal Strength Indicator (hereinafter, referred to as the RSSI). Therefore, a cell coverage is determined, depending upon where the RSSI of a magnitude that enables talking is detected.
However, the characteristics of the base station equipment to be established and used cannot be considered at all if the cell coverage is determined in such a way. That is, the transmission power of the base station equipment can be considered, but the reception characteristics of the base station equipment or the transmission power and reception characteristics of the portable device cannot be considered. Therefore, in case that cells are designed and base stations are established in this way, there may show many differences from the case of actual operation.
In other words, the best way to set a cell coverage that overcomes such problems is to set the cell coverage after the user tries a call with a system actually established. But setting a cell coverage is a factor which determines the number of base stations, and influences the maintenance of the talking quality. Therefore, it is unfeasible to set a cell coverage after establishing base stations.
The following patents each disclose features in common with the present invention but do not teach or suggest the technique for setting an optimal cell coverage of the present invention.
U.S. Pat. No. 5,375,123 to Andersson et al., entitled Allocation Of Channels Using Interference Estimation, U.S. Pat. No. 5,561,841 to Markus, entitled Method And Apparatus For Planning A Cellular Radio Network By Creating A Model On A Digital Map Adding Properties And Optimizing Parameters, Based On Statistical Simulation Results, U.S. Pat. No. 5,561,839 to Osterberg et al, entitled Method And Arrangement In Mobile Telecommunications Networks To Provide For Improved Cell Planning, U.S. Pat. No. 5,521,958 to Selig et al, entitled Telecommunications Test System Including A Test And Trouble Shooting Expert System, U.S. Pat. No. 5,465,390 to Cohen, entitled Method For Laying Out The Infrastructure Of A Cellular Communications Network, U.S. Pat. No. 5,448,616 to Kaewell Jr. et al., entitled Integrated Bit Error Rate Test Function In Analog Channel Unit Of digital Cellular Network, U.S. Pat. No. 5,031,204 to McKernan, entitled Interactive Diagnostic System For Cellular Telephones, and U.S. Pat. No. 4,860,281 to Finley et al., entitled Individual Subchannel Loophack In The PCM Interfaces Of A Digital Telephone Exchange With Control Of The Outbound Path.